Causal relationships between biochemical abnormalities and cancer have been difficult to establish. We have completed a preliminary characterization of several biochemical changes associated with lung tumor induction by urethane, including changes in DNA synthesis, the phosphorylation of specific cytosolic proteins, and increased cAMP-dependent protein kinase activity. To determine whether these biochemical events reflect nonspecific toxicity or are a necessary part of urethane carcinogenesis, we will make use of a series of observations made in this laboratory involving BHT. BHT is a widely used food additive which is not carcinogenic, but in conjunction with urethane can either promote or inhibit tumor formation, depending upon the relative times of administration. BHT alone can cause severe lung damage. We have shown that very small amounts of cedar terpenes can completely block the toxic effects of BHT, probably by influencing drug metabolism. Differences in drug metabolism exist between mice of different ages and between mouse strains which are either genetically susceptible or resistant to urethane tumor induction. It is biochemically sound then to use BHT, terpenes, age and genetic variants as a means of perturbing tumor formation. Mice of different ages and of different genetic backgrounds will be injected with various combinations of urethane, terpenes and BHT. Pulmonary biochemical phenotypes will be determined after treatment. If, for example, the terpenes block tumor promotion by BHT but do not prevent altered protein phosphOrylation, this would suggest that the phosphoproteins are associated, but not causally related to, tumor formation. A temporal sequence of biochemical changes will thus be correlated with the sequence of morphological events during adenoma formation. Insight will be gained into mechanisms of tumor promotion and inhibition, BHT toxicity, and terpene protection.